1. Field of the Invention
This invention relates to a cargo handling system, and more particularly to a braking device for use in such a system for use in controlling cargo motion.
2. Description of the Related Art
Roller systems are commonly used for loading and unloading cargo. In many of such systems, braking devices are utilized to control the motion of the cargo both while it is being loaded and unloaded and when it reaches its loaded position. In the device described in U.S. Pat. No. 5,147,020 issued Sep. 15, 1999 to Scherman et al, continual friction is applied by means of a cylindrical locking shoe which contacts the roller. In U.S. Pat. No. 3,576,242 issued Apr. 27, 1971 to Mumma, a brake shoe device is described which contacts a brake drum to continually provide braking action which increases in response to centrifugal force generated as the speed of rotation increases. In U.S. Pat. No. 5,184,366 issued Feb. 9, 1993 to Rawdon et al. a system is described in which friction brakes extend above roller tines and engage such tines to provide braking action. Other devices are found in the prior art which employ inflatable air bags which are used to raise and retract the rollers.
None of such prior art devices provide a simple operation as does the device of the present invention wherein braking on the cargo is automatically provided at one level when the cargo is moved across the braking device in one direction and at a different level when the cargo is moved across the braking device in an opposite direction. The advantages of applicant's braking device accrue to its ability in a simple mechanism to automatically provide greater braking action on the cargo when it is moving in one direction(usually in a downhill direction) than when moving in the opposite direction(usually an uphill direction).